/Engine/Source/Runtime/UMG/Public/Blueprint/SlateBlueprintLibrary.h
Absolute coordinates could be either desktop or window space depending on what space the root of the widget hierarchy is in.
Transforms AbsoluteCoordinate into the local space of this Geometry.
static FVector2D AbsoluteToLocal ( const [FGeometry](API\Runtime\SlateCore\Layout\FGeometry) & Geometry, FVector2D AbsoluteCoordinate )